美国地质调查局( USGS) 公布了对怀俄明州以及蒙大拿州南部、南达科他州西部和内布拉斯加州部分地区未发现的潜在石油和天然气层的评估。美国地质调查局发现这些地区蕴藏着 4700 万桶石油和 8760 亿立方英尺天然气的技术可采资源。

美国地质调查局称，自上世纪 20 年代开始在该地区进行勘探以来，温德河、比格霍恩和粉河盆地的上古生界油藏已经生产了 40 亿桶石油，按照目前的消耗速度，大约相当于美国 6 个月的消耗量。

美国地质调查局代理局长 Sarah Ryker 表示：“SGS 的能源评估通常侧重于未发现的资源，即科学告诉我们可能存在工业界尚未发现的资源的区域。在这种情况下，经过一个世纪的生产，Wind River、Bighorn 和 Powder River 盆地的上古生界油藏几乎没有未发现的石油。”

评估范围随石油开采技术的变化而变化。1995 年，美国地质调查局对非常规、技术上可采资源进行了评估。 

美国地质调查局地质学家克里斯托弗·申克说：“转向使用水力压裂法进行水平钻井彻底改变了石油生产，我们也因此而改变。”他指出，当美国地质调查局首次评估北达科他州的巴肯页岩矿床时，那里只有几百口垂直井。如今，这一数字已增长到数万口。

美国地质调查局能源资源计划评估美国全球重点地质区内未发现的石油和天然气资源潜力。美国地质调查局使用两种方法：一种用于评估常规石油和天然气资源，另一种用于评估非常规（连续）石油和天然气资源，例如页岩气和煤层气。 

The U.S. Geological Survey (USGS) has released its assessment of potential undiscovered oil and gas formations in Wyoming as well as parts of southern Montana and western South Dakota and Nebraska. The USGS found the areas contain technically recoverable resources of 47 MMbbl of oil and 876 Bcf of natural gas.

Since exploration began in the area in the 1920s, the upper Paleozoic reservoirs of the Wind River, Bighorn and Powder River basins have produced 4 Bbbl of oil—about the same amount the U.S. consumes in six months at the current rate of consumption, USGS said.

“USGS energy assessments typically focus on undiscovered resources—areas where science tells us there may be a resource that industry hasn’t discovered yet. In this case, after a century of production, the upper Paleozoic reservoirs of the Wind River, Bighorn and Powder River basins have little remaining undiscovered oil,” said Sarah Ryker, acting director of the USGS.

The range of assessments produced has changed with the technology available to produce oil.  In 1995, USGS conducted assessments of unconventional, technically recoverable resources. 

“The shift to horizontal drilling with fracking has revolutionized oil production, and we’ve changed with it,” said Christopher Schenk, USGS geologist. He noted that the Bakken Shale deposit in North Dakota had a few hundred vertical wells when the USGS first assessed the area. Today, that number has grown to tens of thousands of wells.

The USGS Energy Resources Program assesses the potential for undiscovered oil and gas resources in priority geologic provinces in the U.S. around the world. Two methodologies are used by the USGS: one for assessing conventional oil and gas resources and one for assessing unconventional (continuous) oil and gas resources, such as shale gas and coalbed gas.